Field of the Invention
Multimetal oxide materials
The present invention relates to multimetal oxide materials of the general formula I EQU A!.sub.p B!.sub.q (I),
where
A is Mo.sub.12 v.sub.a x.sub.b.sup.1 x.sub.c.sup.2 x.sub.d .sup.3 x.sub.e.sup.4 x.sub.f.sup.5 x.sub.g.sup.6 o.sub.x (active phase),
B is x.sub.12.sup.7 Cu .sub.h H.sub.i O.sub.y (promoter phase),
x.sup.1 is W, Nb, Ta, Cr and/or Ce, preferably W, Nb and/or Cr,
x.sup.2 is Cu, Ni, Co, Fe, Mn and/or Zn, preferably Cu, Ni, Co and/or
Fe,
x.sup.3 is Sb and/or Bi, preferably Sb,
x.sup.4 is Li, Na, K, Rb, Cs and/or H, preferably Na and/or K, x.sup.5 is Mg, Ca, Sr and/or Ba, preferably Ca, Sr and/or Ba, x.sup.6 is Si, Al, Ti and/or Zr, preferably Si, Al and/or Ti,
x.sup.7 is Mo, W, V, Nb and/or Ta, preferably Mo and/or W,
a is from 1 to 8, preferably from 2 to 6,
b is from 0.2 to 5, preferably from 0.5 to 2.5,
c is from 0 to 23, preferably from 0 to 4,
d is from 0 to 50, preferably from 0 to 3,
e is from 0 to 2, preferably from 0 to 0.3,
f is from 0 to 5, preferably from 0 to 2,
g is from 0 to 50, preferably from 0 to 20,
h is from 4 to 30, preferably from 6 to 24, particularly preferably from 9 to 17,
i is from 0 to 20, preferably from 0 to 10,
x and y are each numbers which are determined by the valency
and frequency of the elements other than oxygen in I and
and q are non-zero numbers whose ratio p/q is from 160-1 to
1:1, preferably from 20:1 to 1:1, particularly preferably
from 15:1 to 4:1, which contain the component A!.sub.p in the form of three-dimensional regions A which are delimited with respect to their local environment owing to their chemical composition differing from their local environment and are of the chemical composition EQU A Mo.sub.12 v.sub.a x.sub.b.sup.1 x.sub.c.sup.2 x.sub.d.sup.3 x.sub.e.sup.4 x.sub.f.sup.5 x.sub.g.sup.6 O.sub.x
and the component B!.sub.q in the form of three-dimensional regions B which are delimited from their local environment owing to their chemical composition differing from their local environment and are of the chemical composition EQU B x.sub.12.sup.7 Cu.sub.h H.sub.i O.sub.y
where the regions A and B are distributed relative to one another as in a mixture of finely divided A and finely divided B, with the proviso that the regions B contain crystallites of oxometallates of the general formula II EQU Cu Mo.sub.A W.sub.B V.sub.C Nb.sub.D Ta.sub.E O.sub.Y (II),
where 1/(A+B+C+D+E) is from 0.7 to 1.3, preferably from 0.85 to 1.15,
particularly preferably from 0.95 to 1.05, very
particularly preferably 1, (B+C+D+E)/A is from 0.01 to 1, preferably from 0.05 to 0.3,
particularly preferably from 0.075 to 0.15 and
very particularly preferably 0.11 and
Y is a number which is determined by the valency and frequency of the elements other than oxygen in II, of a novel structure type which is defined below by means of its x-ray diffraction pattern (fingerprint). The characteristic and most intense diffraction lines of the novel structure type are shown in the form of interplanar spacings d.ANG.! independent of the wavelength of the X-rays used:
______________________________________ d .ANG.! Intensity %! ______________________________________ 3.40 .+-. 0.3 100 3.54 .+-. 0.3 72 2.27 .+-. 0.2 39 6.79 .+-. 0.3 32 2.56 .+-. 0.2 25 1.57 .+-. 0.2 22 1.87 .+-. 0.2 19 2.96 .+-. 0.3 18 3.56 .+-. 0.3 18 1.64 .+-. 0.2 17 2.66 .+-. 0.2 16 1.59 .+-. 0.2 16 1.55 .+-. 0.2 16 2.67 .+-. 0.2 14 2.00 .+-. 0.2 14 3.04 .+-. 0.3 13 1.57 .+-. 0.2 11 2.36 .+-. 0.2 11 1.44 .+-. 0.2 11 1.70 .+-. 0.2 10 1.51 .+-. 0.2 10 2.35 .+-. 0.2 10 ______________________________________
The stated intensities are relative reference values and are based on the diffraction line having the strongest intensity. Intensity is understood here as meaning the maximum amplitude of the x-ray diffraction band. The associated diffraction angles .crclbar. are obtained from the Bragg relationship: EQU sin .crclbar.=.lambda./2d,
where .lambda. is the wavelength of the x-rays used for x-ray diffraction The above data are based on the powder pattern of an oxometallate Cu.sub.1 Mo.sub.0.9 W.sub.0.1 O.sub.4. The corresponding x-ray pattern was produced on a Siemens D-5000 diffractometer using Cu K.alpha. radiation (40 kV, 30 mA, .lambda.=1.5406 .ANG.). The diffractometer was equipped with an automatic divergence, antidiffusion and counter collimator and a Peltier detector. Regarding the stated line intensities, it should be noted that, in contrast to the position of the lines, the relative line intensities are markedly influenced, in a manner known per se to a person skilled in the art, by the individual crystal orientations established in various preparations for powder analysis, on the basis of the anisotropy of the crystal form, and are therefore less significant for identification of the novel structure type. The quantitative intensities stated above are therefore to be understood as typical values which may vary by up to .+-.50% (based on the stated values) in the case of the lines of strongest intensity (30 -100%, based on the line of strongest intensity).
The novel structure type is to be defined below as HT (High Temperature) copper molybdate type, and crystallites of oxometallates II of the novel structure type defined above are to be referred to as crystallites B*.
The present invention also relates to the oxometallates II themselves and processes for the preparation of oxometallates II and of multimetal oxide materials I. The present invention furthermore relates to the use of oxometallates II or multimetal oxide materials I for catalytic gas-phase oxidations of low molecular weight organic compounds.